Oxygen Radical Scavenging Enzymes Research Articles

Chloroplast superoxide and hydrogen peroxide scavenging systems from pea leaves: Seasonal variations

Levels of chloroplast antioxidants and enzymes that scavenge oxygen racidals were followed in the leaves of pea plants ( Pisum sativum L. cv. Meteor) grown under glasshouse conditions between April 1984 and May 1985. While little variation in pigment levels or superoxide dismutase activity was detected during this period, plants grown in early summer (May–June) contained appreciably higher levels of ascorbate, ascorbate peroxidase and glutathione reductase than plants grown in winter (Dec–Jan.). The role of light intensity in regulating levels of chloroplast antioxidants was examined further using pea plants grown in a constant environment chamber under 100 or 400 μmol m −2 s −1 photon flux density. Chloroplasts isolated from plants grown at the higher light intensity contained significantly higher levels of ascorbate, ascorbate peroxidase, glutathione reductase and dehydroascorbate reductase. These data suggest that light intensity may have an important influence on the level and activity of chloroplast antioxidants and oxygen radical scavenger enzymes.